Permanent well completion apparatus



June 3, 1958 A. P. ROBERTS PERMANENT WELL COMPLETION APPARATUS set 41954 FIG. 2.

Fii i w ms w n M a T r R a R n m A United States Patent 9 2,837,165PERMANENT WELL CONIPLETION APPARATUS Alan P. Roberts, Jim Hogg County,Tex., assignor, by mesne assignments, to Esso Research and EngineeringCompany, Elizabeth,N. J., a corporation of Delaware Applicationoctoberl, 1954, Serial No. 460,114

1 Claim. Cl. 166114) The present invention is directed to apparatus forservicing a well. Briefly, the invention concerns apparatus forconducting treating operations in a cased well having a tubing arrangedtherein, the lower open end of which is positioned above a productiveinterval; the apparatus comprising a packer positioned adjacent thelower end of the tubing for sealing off the annulus between the casingand tubing, a tubular extension member arranged within the tubing andhaving sealing means sealingly engaging the tubing above the packer andextending to adjacent the productive interval, fluid passage meanspositioned in the tubing above and adjacent to the packer and below saidtubular extension sealing means adapted to fluidly communicate thecasing-tubing annulus and the interior of the tubing, and valve means inthefluid passage means opena-ble when the fluid pressure in the annulusand the tubing is below a selected pressure to permit flow through thepassage means and closa'ble to seal off fluid communication between theannulus and the tubing when the pressure in the annulus and the tubingis greater than the above selected pressure.

The apparatus of the present invention may be -em ployed in fracturingimpermeable formations and the like or otherwise opening up fractures orcavities inthe formation, sand, or the stratum. The invention may bealso used in cementing or acidizing-operations in which acid isintroduced into the formation to cause dissolution and increase or causeflow of oil from a formation into the wellbore.

The invention may also housed in sealing oil formations or sealingperforations in a perforated casing and the like.

When the invention is employed in fracturing formations a fracturingfluid such as oil and other similar fracturing fluids containing bodyingand/or weighting agents, such as sand, may be used. As an example of asuitable fracturing fluid, the type described in French Patent No.987,352 published August 18, 1951, may be used. However, it isunnecessary to employ a fracturing fluid containing bodying or weightingagents and it may be desirable to use an oil such as crude oil,distillates, and fractions of crude oil, and the like.

When the invention is used in acidizin-g or fracturing in which acid isforced into formations, the acid may suitably be a mineral acid such ashydrochloric acid, sulphuric acid, nitric acid, hydrofluoric acid, andthe like. Preferably hydrochloric acid is used, and this acid may beused in the form of an acid gel, as it is known to the market. There aremany acid gels available on the market and the acid gel desired may beused as a fracturing fluid if desired. When the fluid is a cementslurry, it is preferred and desirable but not necessary to employ acement of the modified type having a low fluid loss.

Neat cement may also be used satisfactorily even though ithas a highwater loss.

As examples of these cements, the cement slurry may be prepared inaccordance with the patent to Salathiel,

U. S. 2,482,459. Other modified types of cement havinglow fluid losssuch as oil-emulsion cements, oil slurries of cement, and the like, maysuitably be used.

The present invention will be further illustrated by reference to thedrawings in which:

Figures 1 through 6 include a step-wise application of the invention;and,

Figure 7 is a sectional view of a valve suitable for use in Figures 1through 6.

Referring now to the drawings in which identical numerals will beemployed to designate identical parts,

numeral 11 designates a wellbore drilled from the earths surface, notshown, and extending through at least one or through a plurality offormations, strata, or productive intervals A and B, which may beseparated by an impervious formation or interval such as C. Arranged inthe wellbore 11 is a casing 12 which may extend from the top to thebottom of the wellbore 11 but which may extend only the reater length ofthe wellbore. Stating this otherwise, there may be an open hole belowthe casing 12. The casing 12 is cemented in place with primary cement 13to hold the casing securely in place and to seal off strata orformations, such as water, oil, and/ or gas-bearing strata, and thelike.

Arranged in the casing 12 is a tubing string 14 which extends to theearths surface to the wellhead, also not shown.

Arranged in the tubing 14 may be a plurality of gas lift mandrelsprovided with ports 16 and 17 communicating the annulus 18 with tubing14. Tubing 1-4 is arranged above the uppermost of the productiveintervals A and B with the lower open end 19 of the tubing 14 arrangedjust above the interval A. A packer 20, such as illustrated on page 942of the 1952-53 edition of the Composite Catalog of Oil Field andPipeline Equipment isolates the annulus 18 adjacent the lower end 19 ofthe tubing 14. Arranged in the upper mandrel 15 is a gas lift valve 21which may be employed to close port 16. This gas l'iift valve is a valvesuch as illustrated in the Composite Catalogue (1952-53 edition) supraat page 1059 and is used only when gas lift is required.

The port 17 in the lower of the'mandrels 15 maybe opened and closed by avalve such as 21 or a valve such as 22 which is shown in more detail inFigure 7. For the purpose of this description in Figure l, the port 17is provided with a valve such as 21.

In Figure 1 the casing 12 has been perforated in interval B andperforations 22a opened up to allow production, such as hydrocarbons,from the formation B up the casing 12 into the lower open end 19 and upthe tubing 14 to the earths surface. The perforations 22a may have beenformed by lowering a tubing gun perforator through the tubing 14 on awire line or on an electric conductor cable and firing same into theinterval B to open up production.

After the hydrocarbons or other desirable fluids have been produced toexhaustion or substantial depletion from productive interval B orinvasion by water and/ or gas has caused a decline in production of thedesirable well fluids, it may be desirable to obtain production fromanother interval such as A. *It may also be desirable to attempt toreestablish production from interval B, if for some reason productionmay have ceased before this zone was depleted. The valve, such as 21, isremoved from the lower of the mandrels 15 by means of a wire line toolusing a tool such as described at page 1059 of the Composite Catalogue(1952-53 edition) supra and replaced by a valve such as valve 22. Thisvalve is normally open and is closed under a pressure which may bepredetermined. Thereafter, there is'lowered through tubing 14 andsupported, secured and/ or anchored in a landing nipple, such as 23, atubular member 2 4 which serves to lengthen or vary the effective lengthof the tubing 14. The tubular extension 24 provides a passageway 25which allows fluid to be conducted to the in terval B in the region ofperforations 22a.

The landing nipple 23 may be of the type described in the CompositeCatalog (1952-53 edition) supra at page 4063. Anchoring and/or securingmeans, such as pipe engaging mean-s as, for example, slips, latchingdogs, and the like, not shown, may 'be provided on tubular member 24 forreleasably'securing member 24 to landing nipple 23. Arranged adjacentthe upper end of the tubular extension 24 for sealing engagement withthe landing nipple 23 is a sealing means such as chevron packing 26.

The tubular member 24 is provided with a fishing neck 27 which allowsthe tubular member 24 to be lowered through the tubing 14 and retrievedtherefrom by means of a fishing tool attached to a wire line and thelike.

In the showing of Figure 2 flow is established down the tubing 14through the tubular extension member 24 and thence back up the tubingthrough the valve 22 and port 17 into the annulus 18 in the flow patternshown by the arrows.

Thereafter, a cement slurry, such as 28, which may be a modified cementof the type referred to supra, is deposited in the region of theperforations 22a as shown in Figure 3. The casing valve, not shown, atthe wellhead is then closed and pressure allowed to build up in thetubing 14 and the annulus 18 until the pressure is suflicient to closethe valve 22, the operation of which will be described in more detailhereinafter.

Pres-sure is then exerted on the cement slurry 28 through the tubing 14and passageway 25 in tubular extension member 24 to seal theperforations 22a with the cement and to form a filter cake of cement inperforations 22a as illustrated by the buttons or rivet heads 29 shownmore clearly in Figure 4. Thereafter, the casing valve at the wellhead,not shown, is opened and the pressure on the annulus 18 and tubing 14released, which causes the valve 22 to be opened and allowscommunication between the annulus 18 and the tubing 14. Fluid is thenflowed down the annulus 18 to the open end 19 of the tubing 14 andupwardly through the extension member 24 through passageway 25 and upthe tubing 14 to the earths surface. This allows the fluid cement orother fluid material in the casing 12 below the open end 19 be of theshaped charge or bullet gun type, is lowered on wire line 32 through theopen end 19 of the tubing 14 until the perforator 31 is opposite theinterval A. For purposes of this description and for illustrativepurposes only the gun perforator 31 is considered to be one of theshaped charge type which may contain a power pack for firing same or mayreceive electric energy through a conductor cable, extending to the carts surface, which would replace the wire line 32.

In any event, the gun perforator 31 is fired to form perforations in thecasing 12, such as 34, and allow production to be obtained from theinterval A with the flow being in the direction indicated by the arrows.This is shown in Figure 6. In Figure 6 the valve 22 has been replaced bythe valve 21 to close ofl port 17. It is to 'be noted that theoperations in Figures 1 and 6 are substantially identical except forflow in Figure 6 which is from an interval vertically displaced fromFigure l.

The apparatus of the invention may be used also in 4 operations in anopen hole below the casing seat which may allow the treatment of theopen hole for fracturing a formation to render a formation morepermeable than it was before and to increase the flow of desirable fluidtherefrom.

A formation penetrated by the open hole may suitably be treated withacid on which pressure is imposed to cause dissolving or dissolution ofacid reactive materials.

It is also contemplated that such fracturing and acid treatingoperations may be conducted through perforations in the casing byforcing the fluid into an interval or formation penetrated by the wellcasing and perforations in the formation to be drilled or fractured.

The valve, the use of which is described in Figures 2 through 5, isshown more clearly in Figure 7 and is generally indicated by the numeral22. The valve 22 comprises an elongated body member 40 provided withspaced apart packers 41 and 42 between which is arranged a flow port 43.This flow port 43 communicates with the port 17 in the mandrel 15 andallows flow from and to the annulus 18 and the tubing 14.

Arranged in the body member 40 is a bellows member 44 to which isattached a piston 45 connected to valve stem 46. On the free end of thevalve stem 46 is a valve member 47 provided with a sealing means such asO-ring 48 arranged in a recess 48a therein.

The valve 47 serves to close off the chamber 49 which is incommunication with the port 43. The chamber 49 communicates with theannulus 18 through the port 50. The piston 45 has an annular shoulder 51arranged thereon. Embraceably arranged on the piston 45 is a biasingmeans, such as a helical coil spring 52 which normally urges the valve47 away from the seat 53; thus the valve generally indicated by numeral22 is normally in an open position until a predetermined pressureexerted on the valve 47 overcomes the spring 52 and the bellows 44causing the collapse of the bellows 44 and thus closes the valve 47 onthe seat 53 which prevents flow from the port 50 to port 43 or from theport 17 through the port 43 and thence through port 50. Thus, whenpressure is built up in the tubing and easing by closing oh the casingvalve at the wellhead, this pressure causes the valve 47 to seat on seat53.

The pressure at which the valve 22 will be closed may be predeterminedby the size and strength of spring 52 and/or by the charge pressure ofbellows 44. Thus, adjustment of spring tension or bellows chargepressure with the latter preferred may be employed or a combination ofboth may be used. It will be desired to have the valve 22 close at apredetermined pressure less than the safe working pressure of thecasing. With the valve 22 closed off the pressure imposed on the fluid,such as cement slurry and the like, below the lower open end of thetubing may exceed the safe working pressure of the casing above thepacker 20. From the foregoing description of the invention taken withthe drawing, it may be seen that the invention involves forcing fluiddown the tubing 14 and the member 24. Thereafter, pressure is built upin the annulus 18 and the tubing 14 which closes off a valve 22.Pressure in excess of the safe working pressure of the casing 12 abovethe packer 20 is then exerted below the open end of the tubing throughthe tubing. This pressure is higher than ordinarily possible to exert onsuch fluids since in the operation the annulus is isolated.

After the cement has been forced in the perforations, or the fluid hasbeen forced into the formation, pressure is released from the annulus 18and tubing 14 which opens up communication between the annulus 18 andthe tubing 14 re-establishing a flow pattern as has been indicated.Thereafter, excess fluid such as fluid cement and the like is reversedout from the annulus 18 up the member 24 to the wellhead. An interval orformation vertically displaced from the treated formation may, ifdesired, be

perforated by running in a tubing gun perforator after member 24 iswithdrawn.

While I have described the use of the present invention with respect towhat amounts to reverse circulation for removing undesirable fluids fromthe completion interval, it is to be understood that undesirablematerials may be removed by circulating the long-way, that is, downthrough the tubing and tubular member 24 into the annulus 18 through thevalve, such as 22, and up the annulus 18 to the earths surface. It isadvantageous to employ the socalled long-way circulation since in thereverse circulation method it may be necessary to replace the gas liftvalves and to seal the gas lift mandrels to prevent circulation of fluidthrough the gas lift valves from the annulus to the tubing. In thelong-way circulation, replacement of the gas lift valves may bedesirable but is not necessary since gas lift valves, such as referredto, are provided with check valves to prevent flow from the tubing tothe annulus.

Likewise, the use of the invention, while described with respect to aplurality of productive intervals, may be used with only one productiveinterval where the tubing is set above the interval on which the work isto be performed.

When pressure is imposed upon the tubing, the safeworking pressure ofthe casing below the packer 1s not exceeded because of the followingconsiderations:

Current practice in designing casing string utilizes casing havingvaried physical properties. Normally casing having the greater strengthis placed on the bottom and top of the string, while casing havinglesser strength is placed in the center of the string. Thus, if a packerwere set below the casing having the lesser strength, isolation of theannulus would allow application of higher pressure below the packer thancould safely be placed upon the entire length of easing.

Cement is normally employed to seal off all productive formations behindthe casing. If the tubing packer were set below the top of the cement,greater pressures could conceivably be safely placed on the casing belowthe tubing, since this section of easing would be reinforced to somedegree with the cement.

In the Gulf Coast area, for example, weighted mud is normally in thehole when the casing string is set, and remains behind the casing afterthe well is completed. Normally workovers, particularly where permanentcompletion methods are used, employ salt water as the workover fluid.Since the static pressure gradient of the fluid behind the casing isnormally greater than that of the salt water inside the'casing and sincethis differential pressure which tends to collapse the casing increaseswith depth, it is conceivable that greater pressures may be 6 safelyapplied inside the casing near the bottom of the hole than at the top ofthe hole.

In some instances it is conceivable that pressure applied inside thecasing may be transmitted to some extent through casing perforations tofluid behind the casing for some distance above the perforations; thus,the differential pressure tending to burst the casing may be lessened insections near the casing perforations.

Any one or a combination of the several mentioned factors may operate toallow the present invention to be employed when pressures exceeding whatis normally considered safe-working pressure of the casing below thepacker are placed on the tubing.

The present invention allows many advantages to be obtained, principallythe use of pressures in conducting operations, which heretofore were notpossible since the safe working pressure of the casing ordinarily wouldbe exceeded.

The nature and objects of the present invention having been completelydescribed and illustrated, what I wish to claim as new and useful andsecure by Letters Patent Apparatus for conducting treating operations ina cased well having a tubing arranged therein, the lower open end ofwhich tubing is positioned above a productive interval, said apparatuscomprising a packer positioned adjacent the lower end of said tubing forsealing off the annulus between said casing and tubing, a tubularextension member arranged within said tubing and having sealing meanssealingly engaging said tubing above said packer and extending toadjacent said productive interval, and fluid passage means positioned insaid tubing above and adjacent to said packer and below said tubularextension sealing means adapted to fluidly communicate saidcasing-tubing annulus and the interior of said tubing, valve means insaid fluid passage means .openable when the fluid pressure in saidannulus and said tubing is below a selected pressure to permit flowthrough said passage means and closable to seal off fluid communicationbetween said annulus and said tubing when the pressure in said annulusand said tubing is greater than said above selected pressure.

References Cited in the file of this patent UNITED STATES PATENTS1,050,244 Smith Jan. 14, 1913 2,087,297 Pew July 20, 1937 2,360,311Ausburn et al. Oct. 17, 1944 2,675,880 Baker Apr. 20, 1954 2,716,454Abendroth Aug. 30, 1955 2,749,989 Huber June 12, 1956 2,760,578 TauschAug. 28, 1956

